Crankpin truing device



Seph 26, 1939.

F. PosTMA CRANKPIN TRUING DEVICE I Filed March 28, 1938 Siwa/VWO@ Pian/c P06757@ www Patented Sept. 26, 1939 UNITED STATES PATENT OFFICE CRANKPIN TRUING DEVICE Frank Postma,

ApplicationMarch 28,

3 Claims.

This invention relates to a device for grinding or truing worn crank pins of crank shafts for internal combustion engines and the like.

The primary object of the present invention is to provide an improved crank pin truing device of the type adapted to treat the crank pins without removing the crank shaft from the motor and embodying a connecting rod having a crank pin bearing provided with an abrasive or grinding surface, and adapted to be substituted for the usual connecting rod of the motor to perform the grinding operation.

The primary object of the present invention is to provide a device of the above kind which is adjustable in length so as to adapt the same for use in connection with engines of various makes and sizes having connecting rods of diiferent lengths, thereby avoiding the y'necessity of providing a separate grinding or truing device for use in connection with each different make or type of engine.

Another object ofthe present invention is to provide a grinding or truingdevice of the above kind in which the crank pin bearing thereof is provided with an abrasive liner that projects beyond the sides of said bearing, and in which said crank pin bearing is of lesser width than the average length of engine crankA pins, whereby the appliance may be employed to grind or true crank pins of different lengths by varying the extent that the abrasive liner projects beyondthe sides of said crank pin bearing.

A still further object of the present invention is to provide a device of the above kind having a Wrist pin bearing at one end which is adjustable to receive wrist pins of various sizes and which may be set to securely hold the wrist pin against turning or to permit turning thereof, as the case may require in different types of engines.

With the above objects in View, and others that will become apparent as the nature of the invention is better understood, such invention consists in the novel form, combination and arrangement of parts hereinafter more fully described, shown in the accompanying drawing and claimed.

In the drawing:

Figure 1 is a fragmentary vertical sectional View of an engine, showing the application of my invention thereto.

Figure 2 is a view partly in edge elevation and partly in longitudinal section, of the present grinding or truing device.

Figure 3 is a side elevational view thereof, partly broken away and in section; and

Figure 4 is a top plan view of the cap section Ridgewood, N. J.

1938, Serial No. 198,521

of the crank pin bearing forming part of the device shown in Figures 1 to 3 inclusive.

Referring in detail to the drawing, the present device is in the form and construction of an engine connecting rod and consists of a body or shank which is extensible or adjustable in length and consists of adjustably connected sections 5 and E. The body or shank of the device is provided at one end with a wrist pin bearing consisting of a fixed or integral jaw 1 and a cap jaw 8 adjustably connected by bolts 9 so as to accommodate wrist pins of different sizes. The wrist pin shown at ID may be either firmly held in the bearing l, 8 or loosely held for rotation therein as may be required. In order to secure efficient gripping of wrist pins of various sizes when the latter are required to be firmly held, the jaws l and 8 of the wrist pin bearing are preferably of the V-type as illustrated. This type of wrist pin bearing also provides a secure contact at four points in such a manner as to receive the full benefit of the guiding action of the wrist pin and piston assembly, thereby insuring a finished journal which will be parallel with the plane of crankshaft rotation.

At the other end, the body or shank of the device is provided with a crank pin bearing consisting of a fixed or integral section Hl and a cap section ll, substantially as is the corresponding bearing of a connecting rod. 'Ihe cap section Il of the crank pin bearing is connected to the fixed or integral section lil by means of the usual bolts l2, and each of the sections It and Il is provided with removable grinding or polishing segments i3. These segments may be of any preferred construction, but are preferably of the type shown in my co-pending application for patent upon Abrading device, Serial Number 173,014, led November 5, 1937 and allowed November 27, 1937. In this case, the grinding or polishing segments have openings as at M to receive the pins i5 carried by and projecting inwardly from the bearing sections lll and Il, whereby said grinding or polishing segments are restrained against rotation with the crank pin. It will be noted that the crank pin bearing'is narrow so as to accommodate a crank pin of minimum length, the grinding or polishing. segments I3 projecting beyond the sides of this bearing to. engage the crank pin throughout the length thereof. By providing grinding or polishing segments of different lengths, crank pins of different lengths may be accommodated and ground or trued throughout the length thereof. In some cases, the crank pin of an engine has a slight longitudinal taper, and means is provided for laterally tilting the cap section II of the crank pin bearing to such slight extent as may be necessary to take care of a situation of this kind. This means may simply consist of set screws I threaded through the ends of the cap section II at opposite sides of the bolts I2 and bearing against the ends of the fixed or integral bearing section I0. Obviously, by proper relative adjustment of the set screws I5, the desired slight lateral tilting of the cap section II of the crank pin bearing may be effected, the grinding or polishing segments I3 being of course prepared to allow this adjustment. By providing the features or characteristics above described, the present device is adapted to supply practically all of the requirements necessary to permit the device to operate in connection with engines of various types and sizes within reasonable limits. The only other important requirement is that the grinding or polishing segments I3 afford the necessary inside diameter to take care of a crank pin of any outside diameter. This is accomplished by making the inside diameter of the crank pin bearing relatively large and varying the thickness of the grinding or polishing element composed of segments I3. In other words, the use of thin grinding or polishing segments will permit truing or grinding of crank pins of maximum size, and by increasing the thickness of said grinding or polishing segments, crank pins of different sizes may be taken care of from the maximum to a minimum size or diameter. Thus, a single device is provided capable of universal use with engines of different makes and sizes, thereby avoiding the necessity of providing a separate grinding or truing device for each size or type of engine.

The body or shank of the device may be made extensible or adjustable in length in any suitable or preferred manner. As illustrated, the shank section 5 is bifurcated and straddles the shank section 6 as well as being slidably tted between ribs I6 projecting laterally from opposite sides of the shank section 6 along its longitudinal edges. The ribs I6 thus maintain the sections 5 and 6 in alinement, and the legs of the bifurcated section 5 are securely clamped together against opposite sides of the section Ii by means of clamping bolts I'I extending through one leg of section 5 and threaded into the other leg thereof, as well as passing through a longitudinal elongated slot I8 in the section 6. By loosening the clamping bolts I'I, the length of the connecting rod grinding device may be adjusted, and the adjustment may be secured by again tightening said bolts I1. For purposes of securing more positive adjustment, the contacting surfaces of the legs of section 5 and section 6 along opposite sides of the slot I8 may be provided with transverse interengaging teeth I9 and 20 or other suitable roughened contacting surfaces.

In using the device described, the connecting rod of the motor is removed, and in its place the present device is positioned, the crank pin bearing being adjusted to afford the proper grinding effect. The wrist pin bearing of the device is also connected to the piston in the usual manner prior to the insertion of the piston in its cylinder and the connection of the device to the crank pin. When adjusted in this manner, the crank shaft is then rotated slowly until the crank pin is properly trued, the necessary adjustments being made with respect to the cap member II so as to finally produce the necessary trued condition of the crank pin. The general advantage of a device of the present type is that the operation is both simple and economical, saves time and expense by reason of treating the crank shaft without removal from the motor, and insures extreme accuracy by truing the crank pin round and with respect to the cylinder bore alinement. The specic improvements and features of the present device effectively carry out the stated objects of the present invention, and minor changes in the details of construction illustrated and described are contemplated within the spirit and scope of the invention as claimed.

What I claim as new is:

1. A device for truing worn crank pins of engine crankshafts, comprising a body in the form of an engine connecting rod and composed of a plurality of sections longitudinally adjustable relative to each other to vary the length of said body in accordance with the requirements of different engines, said body including a wrist pin bearing at one end and a crank pin bearing at its other end having a grinding surface engageable about the crank pin, said wrist pin bearing being adjustable to receive wrist pins of various sizes and embodying a xed section and a cap section connected by bolts to loosely receive or rmly grip the wrist pin as occasion may require, said wrist pin bearing sections being of. V-shape.

2. A device for truing worn crank pins of engine crankshafts, comprising a body in the general form of an engine connecting rod and composed of a pair of sections longitudinally adjustable relative to each other to vary the length of said body in accordance with the requirements of different engines, and means to rigidly secure said sections in any desired relative position of longitudinal adjustment, one of said sections having a Wrist pin bearing at its outer end adjustable to t wrist pins of various sizes, the other section having a crank pin bearing at its outer end adjustable to fit crank pins of various sizes, said crank pin bearing having a grinding surface engageable about the crank pin.

3. A device for truing worn crank pins of engine crankshafts, comprising a body in the general form of an engine connecting rod and composed of a pair of sections longitudinally adjustable relative to each other to vary the length of said body in accordance with the requirements of different engines, means to rigidly secure said sections in any desired relative position of longitudinal adjustment, one of said sections having a wrist pin bearing at its outer end adjustable to t wrist pins of various sizes, the other section having a crank pin bearing at its outer end adjustable to t crank pins of various sizes, said crank pin bearing having a grinding surface engageable about the crank pin, said crank pin bearing including a cap section, and means for laterally tilting said cap section.

FRANK POSTMA. 

